The program of research outlined in this proposal is designed to continue our attempts to develop a behavioral system in the marine mollusc Aplysia in which one can examine in appropriate cellular detail the mechanisms of a variety of short-term and long-term nonassociative and associative types of learning. Toward this end we plan in the proposed research to carry out three interrelated types of studies: 1) an analysis of the molecular mechanisms of two short-term nonassociative forms of behavioral modification habituation and sensitization, 2) an analysis of the relationships between a) short-term habituation and long-term habituation and b) between short-term sensitization and long-term sensitization, 3) an attempt to establish associative learning to analyze it on the cellular level.